What exactly is a laser? A laser is a
(41) .......... that intensifies light, that is, it makes it stronger.
(42) .......... ordinary light rays travel in different directions, laser beams all travel in a straight line,
often for great
(43) .......... .
The first laser was
(44) .......... by Theodore Maiman in 1960.
It was small enough to hold in one hand,
(45) .......... its beam of light was the most
(46) .......... that had ever been produced on earth.
Today lasers both large and small are employed in many different situations; doctors can perform delicate
(47) .......... using them and low-power laser beams at supermarket check-outs
(48) .......... prices to be read
(49) ..........
There are few other
(50) .......... that have such a wide range of uses.